Better MPG w/ Sport Mode?

Y

Yuj

Member
Hi guys,

I'm currently driving a stick shift '03 z4 2.5i (63k miles) and I'm getting about 23mpg with sport mode off. However, with sport mode on, I get about 26mpg . I'm driving the exact same routes every day and when I put it in sport mode I don't change my driving behavior at all. Is there any possible reason why I get so much better fuel economy in sport mode?

Other side notes:
- I calculate mpg by using the trip odometer vs. gallons pumped at the same gas station every time
- I get gas only when low fuel light comes on
- Mileages for each set of results (sport mode on vs off) are averaged over 3 fill ups
- The car is my daily driver; my route is approx 75% hwy 25% local
 
An ICE tends to be more economical if you get up to speed (relatively) quickly, and then cruise at a constant speed. Chances are the more aggressive throttle map is ensuring you get up to speed more quickly, and therefore using less fuel in the long-run. It's counter-intuitive, but it's to do with losses in the fuel delivery system (or so I'm told). Obviously flooring it won't have the same effect :P
 
23mpg :!: You must be having fun, I'm getting 34-36 mpg in my 2003 2.5 se on mixed roads, but for some reason get less with the sport button on, can't think why :driving:
 
Ewazix said:
23mpg :!: You must be having fun, I'm getting 34-36 mpg in my 2003 2.5 se on mixed roads, but for some reason get less with the sport button on, can't think why :driving:
Click to expand...
US gallon may be the difference?
 
Ewazix said:
mmm-five said:
Ewazix said:
23mpg :!: You must be having fun, I'm getting 34-36 mpg in my 2003 2.5 se on mixed roads, but for some reason get less with the sport button on, can't think why :driving:
Click to expand...
US gallon may be the difference?
Click to expand...

Dohhh :oops:
Click to expand...

Nothing like enough to make that difference - 23 x 1.2 = 27.6 Still missing a good few mpg.

I wonder if driving over extended periods and in mixed traffic actually causes you to be more gentle on the thottle in sport mode, to overcome the jerkiness that it's over sensitive range produces. End up driving smoother, which equates to better mpg??
 
Yeah being harder on the throttle and using it over less time is known to be better for fuel consumption... Primarily this is due to pumping losses involved in petrol engines (air gets through an open throttle body much easier than an almost closed one!)
 
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